Varytale describes itself as "a publisher and retailer of Interactive books". The books in question are read in a browser, and present choices, mainly at the end of the the segments. It seems they also use a somewhat unusual notion of sections of text that can be "finished". They seem to go for a serious the, and also point out that they are not about gaming but about telling stories. (just to be clear, I am not saying that games cannot be a serious as stories, interactive or otherwise). There's a story by Emily Short, who is one of the more respected authors of interactive stories. The authoring tools at varytale are closed for the moment, although you can request an account by e-mail. From what they say it's an online authoring tool, and it supports stateful stories. There Is also something called story points which control how fast you can read a story, and the option to charge for the stories either up front or to access parts of the story.